Apparatus for use in driving tunnels

ABSTRACT

Apparatus for use in driving tunnels and having an advanceable shield formed by a plurality of elongate members disposed sideby-side in contact with the wall of the tunnel. The members are supported by two frames interconnected through piston and cylinder units. Each elongate member has sets of apertures with guide members therein defining guide surfaces which selectively receive spring-loaded slidable pins carried by the frames and respectively allocated to the members. The pins carried by one frame each have inclined surfaces at its outer end which engage on inclined guide surfaces in each associated aperture to permit the pin to retract automatically upon relative movement between the frame and the member having the aperture in question along the axis of the tunnel. The pins carried by the other frame are each manually rotatable about its axis through 180* to bring an abutment surface at its outer end into engagement with one of two opposite surfaces in an associated aperture extending parallel to the axis of the pin whereby the pin can selectively lock the frame to the member having the aperture in one or the other direction along the axis of the tunnel. Those pins carried by the other frame also each have an inclined surface engaging on one of two converging inclined surfaces in the associated aperture so that the pin can be retracted automatically when relative movement occurs between the frame and the member having the aperture in one direction or the other.

United States Patent 1191 Foik [ 1 Feb. 11, 1975 1 APPARATUS FOR USE IN DRIVING TUNNELS [75} Inventor: Adolf Folk, Altlunen, Germany [73] Assignee: Gewerkshaft Eisenhutte Westfalia,

Westfalia, Germany [22] -Filed: Apr. 18, 1973 [21] Appl. No.: 352,173

[30] Foreign Application Priority Data Apr. 20, 1972 Germany 2219271 [52] US. Cl. 61/84, 61/85 [51] Int. Cl. E0lg 3/02 [58] Field of Search 61/84, 85, 41 A, 42, 45, 61/63; 299/11, 31, 33

[56] References Cited UNITED STATES PATENTS 1,275,910 8/1918 Hamilton 61/85 1,855,466 4/1932 Barber et al...... 61/85 2,196,100 4/1940 Caputo 61/85 3,581,507 6/1971 Stevens 61/85 3,668,874 6/1972 Krings 61/41 A 3,716,997 2/1973 Rees et a1. 6l/8S FOREIGN PATENTS OR APPLICATIONS 325,396 1/1903 France 61/85 1,086,723 8/1960 Germany 61/85 Primary ExaminerDennis L. Taylor Attorney, Agent, or Firm-Thompson, Birch, Gauthier & Samuels [57] ABSTRACT Apparatus for use in driving tunnels and having an advanceable shield formed by a plurality of elongate members disposed side-by-side in contact with the wall of the tunnel. The members are supported by two frames interconnected through piston and cylinder units. Each elongate member has sets of apertures with guide members therein defining guide surfaces which selectively receive spring-loaded slidable pins carried by the frames and respectively allocated to the members. The pins carried by one frame each have inclined surfaces at its outer end which engage on inclined guide surfaces in each associated aperture to permit the pin to retract automatically upon relative movement between the frame and the member having the aperture in question along the axis of the tunnel. The pins carried by the other frame are each manually rotatable about its axis through 180 to bring an abutment surface at its outer end into engagement with one of two opposite surfaces in an associated aperture extending parallel to the axis of the pin whereby the pin can selectively lock the frame to the member having the aperture in one or the other direction along the axis of the tunnel. Those pins carried by the other frame also each have an inclined surface engaging on one of two converging inclined surfaces in the associated aperture so that the pin can be retracted automatically when relative movement occurs between the frame and the member having theaperture in one direction or the other.

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1 APPARATUS FOR USE IN DRIVING TUNNELS BACKGROUND TO THE INVENTION The present invention relates to an apparatus for use in driving tunnels or the like.

it is known to utilize an advanceable driving shield or lining composed of a plurality of elongate members arranged side-by-side in contact with the tunnel wall during the excavation of the tunnel. This shield serves to support the wall of the tunnel and prevents collapse of the tunnel in the region adjacent the face or heading being worked by cutting means. Normally the members of the shield are selectively connected to a supporting frame which can be moved by shiftingmeans to cause the shield to advance in the heading direction.

Hitherto there has been a considerable amount of time-consuming manual labour involved in connecting the elongate members to the supporting frame and long delays and damage can result when a connection is incorrectly released or made.

A general object of this invention is to provide an improved form of apparatus employing an advanceable shield.

SUMMARY OF THE INVENTION frames which are selectively automatically connectible with and disconnectible from the elongate members. In contrast to the prior art only a small amount of manual labour is required to connect the elongate members to the second frame which serves to advance groups of members in a sequential manner. Moreover, if the devices pertaining to the frame are incorrectly set there is no danger of damaging the structure.

Preferably the frames have a shape conforming with the cross-section of the tunnel, e.g., circular. The displacing means would normally be in the form of a plurality of doubleacting piston and cylinder units. Each elongate member would usually have sets of spacedapart apertures for receiving movable pins forming part of said locking devices, the pins being biased with springs to enter the associated apertures. One set of apertures of each member would be associated with the locking devices of one frame and another set of apertures would be associated with the locking devices of the other frame.

Preference is given to a construction wherein each of the pins of the locking devices provided on the first frame is adapted to automatically retract from an associated aperture upon relative movement between the first frame and the member having said aperture in either direction along the axis of the tunnel. Each of the pins of the locking devices on the second frame can then be capable of being manually set into one of three operating positions whereat the pin is retracted from an associated aperture or is set to prevent relative movement between the second frame and the member having said aperture along the axis of the tunnel in either of two opposite directions.

The first frame may be of l-shaped cross-section with the pins of the locking devices thereof extending paral- LII lel to the central web thereof and the second frame may be of hollow rectangular cross-section with the pins each being disposed in a guide bush extending between inner anad outer side walls of the second frame.

in general, in order to force the pins out of their apertures during the forward movement of the members in the direction of the heading the apertures are preferably lined with guide members with guide faces engageable with similar faces of the pins. It is advantageous to adopt two inclined guide faces extending in opposite directions to each other and inclined away from the direction of advance. Both said inclined faces may have the same or different angles of inclination.

More particularly, each pin of the locking devices provided on the first frame preferably has an outer end facing the associated member with two inclined faces converging outwardly and each associated aperture in the associated member is provided with one or more guide members provided with inclined faces engageable with said faces of the pin. The pin may be biased with a stack of cup springs towards the associated elongate member, and preferably a mechanism is provided for adjusting the force exerted on each pin by the associated stack of cup springs.

in the case of the pins of the locking devices provided on the second frame, preferably the pin is slidably and rotatably guided and has a shaped outer end with the face extending parallel to the longitudinal axis of the pin and another adjoining face inclined in relation to said one face, each associated aperture in the associated member being provided with one or more guide members with faces selectively engageable with said faces of the pin. Preferably each of said faces of the guide member or members is composed of two opposite faces extending parallel to the axis of the pin and each engageable with said one face of the outer end thereof and the two inclined faces inclined at equal angles and converging towards the pin, each said inclined face being engageable with said another face of the outer end of the pin. The end of each pin remote from the shaped end thereof is loaded with a spring force and is provided with a lever for effecting rotary movement of the pin to select said operating positions, the pin being rotated through 180 to bring one face thereof into engagement with either of said opposite faces, and wherein the frame is provided with cams of semi- V circular configuration engageable with the lever intermediate the offset positions of the lever to cause the pin to be retracted from an associated aperture in an associated member against said spring force. In both directions of movement the pins can then be automatically moved against the spring pressure into their released position.

The second frame is used to advance separate groups of members by selectively actuating the locking devices by hand by means of the levers to lock the desired members to the second frame. The form of locking device for the first frame serves to secure the latter firmly against the members by friction in such a manner that the frame forms a positively fixed anchor or abutment for moving the second frame and members connected thereto. On the other hand, the forward movement of individual members or groups of members relative to the first frame can be accomplished without releasing the corresponding pins by hand. When, after advancing all the members, the first frame must itself be brought up it is only necessary to operate the shifting units since the pins of the locking devices thereof will be released automatically. The pins of the locking devices of the second frame which are not to lock with the associated member also slide along one of the inclined faces in the associated apertures to autmatically retract the pins. By turning any of these pins around its axis through l80 the direction of locking is reversed so that the second frame is either fixed to the members to be moved or fixed to said member in such a way that when the first frame is drawn forward the second frame forms a positively anchored abutment. In both positions of each pin the pin will be automatically released in one direction so that under no normal circumstances can damage occur.

The invention may be understood more readily and various other features of the invention may become more apparent from consideration of the following description.

BRIEF DESCRIPTION OF DRAWINGS An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic sectional side view of apparatus made in accordance with the invention;

FIG. 2 is an enlarged, part sectional side view of part of the apparatus showing particularly the locking devices of the frames;

FIG. 3 is an enlarged part sectional side view of one form of locking device used in the apparatus;

FIG. 4 is an enlarged part sectional side view of another form oflocking device used in the apparatus; and

FIG. 5 is a plan view partly in section, of a further part of the apparatus showing in particular two of. the locking devices depicted in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT Referring initially to FIG. 1, the apparatus is depicted during use in the construction of a tunnel or adit of circular cross-section. The apparatus is located adjacent the heading or working face and is composed of a plurality of elongate members or planks 11 arranged side-by-side to form a shield or lining for the tunnel wall. In known manner this lining formed by the planks 11 is advanceable towards the face 10 and to this end each plank 11 is slidably guided for longitudinal movement. The planks 11 are made from metal and each plank 11 has a knife-edge 17 at its leading end adjacent the face 10. The planks 11 are supported on two spaced apart frames 12 and 13. Each frame is of circular configuration to match the tunnel although other configurations e.g., portal shapes are possible. The frames 12 and 13 are interconnected by means of double acting piston and cylinder units 14 arranged symmetrically around the circumference of the frames. Each unit 14 has a piston rod 15 pivotably connected via a joint 16 to the frame 13. Each plank 1 has sets of two apertures 18, 19 for receiving locking devices of the frame 12 and the frame 13 respectively.

Each set of apertures is in this example composed of three apertures 18 and three apertures 19 spaced apart longitudinally on the plank II by a distance corresponding to the stroke of the units 14. The construction and operation of the locking devices will be described in more detail hereinafter. At this stage it may be convenient to describe the operation of the apparatus in general terms.

Normally the face 10 is cut away by a cutting head not shown in the drawing and not forming any part of the present invention. From time to time the apparatus is moved up by operation of the units 14. The units 14 are double acting and the frames 12, I3 can move in the direction of arrow A or B of FIG. 1. In general, the units 14 are used to displace one frame relative to the other frame, and the stationary frame 12 is clamped or locked to some of the planks 11 by the locking devices thereof so as to act as an abutment for the units 14 and the frame 13 which moves. More particularly, two or three of the planks 11 are locked to the frame 13 with the locking devices thereof and the remainder of the planks 11 are secured to the stationary support frame 12, again with the locking devices thereof. The units 14 are then operated to move the advancing frame 13 in the direction of arrow A. The locking devices of the frame 13 are now released from the advanced planks 11 and the units 14 are operated to move the frame 13 back in the direction of arrow B. Two or three more planks 11 are now secured to the frame 13 with the aid of the locking devices and the frame 13 is again advanced to draw these planks 11 up. This sequence is repeated a number of times until all the planks 11 are advanced. Then the planks 11 are all secured to the frame 13, the frame 12 is released from the planks l1 and the units 14 are operated to advance the frame 12. The complete sequence starting with the advance of two or three planks 11 with the frame 13 can then recommence at the appropriate time.

It will be appreciated that the locking devices associated with the frames 12, 13 have to be capable of being selectively locked to or released from the planks 11. The locking devices of the frame 12 are somewhat different from the locking devices of the frame 13.

FIG. 3 depicts one of the locking devices of the frame 12. As shown in FIG. 3 the frame 12 consists essentially of a one-piece structure of I-shaped cross-section. A locking device is provided on the frame 12 for each of the planks 11, the locking device being engageable with any one of the apertures 18 in the associated plank 11. Each locking device has a slidable pin 20 extending parallel to the central web of the frame 12 and having an outer end formed with converging faces 21 extending at 45 to the axis of the pin 20. The pin 20 is slidably guided by blocks 22 welded within the frame 12 to project outwardly through an aperture in the outer side wall of the frame 12. The pin 20 is partly hollow and receives a bolt 26. The inner end of the pin 20 has a head 23 which forms a seat for a stack of cup springs 24 which are seated at the other end on a shaped disc 25 located in an aperture in the inner side wall of the frame 12. The bolt 26 extends through the springs 24 and the disc 25 and is in screw-threaded engagement with the disc 25. A lock nut 28 is threaded on the bolt 26 and is engageable on the outer face of the inner side wall of the frame 12. By releasing the nut 28 and rotating the head 27 of the bolt 26, the disc 25 can be displaced to vary the biasing force applied by the springs 24 on the pin 20.

The apertures 18 in the associated plank 11 are each lined with guide members 29, 30. These members 29, 30 have faces 29, 31 which converge at the longitudinal axis of the pin 20. The angles of inclination of the faces 29, 31 are dissimilar with the angle of inclination of the faces 29' being smaller than the angle of inclination of the face 31. The angle of inclination of the face 29 is preferably about l5-25 whereas the angle of inclination of the face 31 is preferably 45 to match the inclination of the surface 21 of the pin 20. The frame 12 can thus be advanced in the direction of arrow A without the planks 11 since the pins 20 of the locking devices of the frame 12 will slide smoothly over the as sociated faces 29 so that the pins 20 are retracted. If any of the planks 11 is attached to the frame 13 as described hereinafter, for positive movement therewith the associated face 31 will slide over the surface 21 of the pin 20 and force the pin 20 to retract. Otherwise the planks 11 are firmly held against displacement in the direction of arrow A by the engagement between the faces 31, 21 and the engagement of the planks 11 with the tunnel wall.

The spring-loaded pins 20 of the frame 12 are not operated manually but the friction and locking forces of the pins 20 can be easily and accurately varied by the adjustment screws 26. It can be seen that the lined apertures 18 in planks 11 associated with the pins 20 in the frame 12 serve to increase the frictional resistance between the frame 12 and the planks 11. The forces needed to release the pins 20 is different in both directions in view of the different inclinations of the faces 29', 31. The frame 12 constitutes an anchored abutment during the advance of the frame 13. On the other hand, the frame 12 can be moved in the direction of arrow A without causing movement of the frame 13 by reaction forces.

FIGS. 4 and 5 depict the form of locking devices provided on the frame 13. As shown in FIG. 4, the frame 13 is of rectangular hollow cross-section and is composed of plates welded together. Guide bushes 35 are welded into the frame to extend between the outer and inner faces thereof. The locking device for each plank 11 is composed of a slidable pin 36 disposed within an associated one of the bushes 35. The outer end of the pin 36 has a shaped portion forming a face 37 extending parallel to the longitudinal axis of the pin 36 and an inclined face 38. Each aperture 19in each plank 11 has guide members 39, 40, 41 welded therein. The guide member 39 has two inclined faces 42, 43 converging towards the associated pin 36 and inclined at the same angle. The inclined face 38 of the pin 36 can engage either of these faces 42, 43 and provision is made to rotate the pin 36. To this end each pin has a lever 44 connected to the end thereof remote from the shaped end. The members 40, 41 have end faces 55 either of which is engageable with the face 37 of the pin 36. As shown in FIG. 5, each adjacent pair of pins 36 is interconnected by means of a spring 45. The spring 45 is a spiral spring carried on a rod 46 and having arms 47 which are located in grooves 48 in the ends of the pins 36 connected to the lever 44. The spring 45 serves to bias the pins 36 into the apertures 19 of the associated planks 11. The inner wall of the frame 13 has earns 49 thereon of semi-circular shape. These cams 49 each serves to engage the associated lever 44, as the latter is swung in the direction of arrow S (FIG. 5) to rotate the pin 36 connected thereto, to cause the pin 36 to withdraw from the hole 19 and to retract into the frame 13. Thus, if the lever 44 is only swung through 90 from the position depicted in FIG. 5 it rests on the crown of the associated cam 49 to maintain the associated pin 36 in the retracted position. The lever 44 can however be swung through 180 from the position shown in FIG. 5 to reverse the position of the faces 37, 42 of the pins 36. In

contrast to the pins 20 the pins 36 are operated manually. The pins 36 can be lifted out of the apertures 19 by placing the levers 44 on the crown of the cams 49 to release the locking effect of the pins 36 in both directions or the pins 36 can be brought into either of two operating positions with the faces 36 engaging the faces 55 of either of the members 40, 41. In normal operation an operator only operates the pins 36 since the pins 20 can be automatically released in both directions of movement. The operation of the locking devices associated with the frames 12, 13 will now be described in the context of the overall operation of the apparatus with reference to FIG. 2.

FIG. 2 depicts the condition when the frame 12 is locked to the individual planks 11 by the pins 20 engaging in the apertures 18. Two or three planks 11 are now to be advanaced simultaneously in the direction of arrow A. To achieve this, the levers 44 pertaining to these planks 11 are turned into the position shown in FIG. 2 where the pins 36 are forced by the springs 45 into the associated apertures 19. The pins 36 thereby have their faces 37 engaging on the faces 55 of the members 40, and their faces 38 engaging on the faces 42 of the members 39. These planks 11 can now be advanced with the frame 13 by operating the units 14. In

the case of the other remaining planks 11 the pins 36 are in the position in which the faces 38 engage .on the faces 43 of the members 39. When the frame 13 advances the pins 36 associated with the planks 11 which are to remain stationary are automatically lifted out of their respective apertures 19 as the faces 38 slide along the faces 43. Also, as the planks l1 moved with the frame 13 advance the pins 20 of the frame 12 are forced out of their apertures 18 by the engagement of the faces 21, 31 and hence these planks 11 are moved forward while the remaining planks 11 and the frame 12 are stationary. When the planks 11 secured in the described manner to the frame 13 have completed their advance the pins 20 of the frame 12 automatically enter the next apertures 18 in the set of apertures 18 in the planks 11 which were advanced. Also the pins 36 of the frame 13 which were retracted also enter the associated apertures 19 of the advanced planks 11.

The frame 13 is now moved back in the direction of arrow B after the pins 36 which block the movement of the frame 13 in the direction of arrow B with their faces 37 resting on the faces 55 of the members 41, are turned through into the position shown in FIG. 2. During the movement of the frame 13 the pins 36 are forced out of their apertures 19 against the forces of the springs 45 by the engagement of the faces 38, 42. When the frame 13 reaches its rear position the pins 36 again enter the relevant apertures 19. Another group of planks 11 can now be advanced in the described manner. The whole cycle is repeated until all planks 11 are advanced.

It is now necessary to move the frame 12 in the direction of arrow A by means of the units 14. During the displacement of the frame 12 the frame 13 acts as the abutment. The pins 36 are initially turned through 180 in such a manner that the faces 37 rest on the faces 55 of the members 41. The frame 13 and the planks 11 are thereby locked against any movement in direction of arrow B. Since the planks 11 remain in frictional engagement with the wall of the tunnel no movement of planks 11 nor of the frame 13 is possible in direction of arrow A. FIG. 2 jointly with FIGS. 3 and 4 show that when the frame 12 is moved in direction of arrow A the tapered ends of the pins 20 are gently pressed out of the apertures 19 by the faces 29' of the blocks 29.

When the frame 12 is moved forward in the described manner the pins 20 engage in the appropriate apertures 18 of the planks 11. The next advancing cycle can then take place as described above.

The above-described operating roles of the frames 12, 13 can be reversed with the frame 12 serving to advance the planks 11. The planks 11 can cover the whole excavated cross-section as shown or only part of the excavated profile, e.g. the planks 11 may extend over the roof and sidewalls of the working only.

i claim:

1. In an apparatus for use in driving tunnels or the like, the apparatus including two parallel, spaced-apart, substantially circular frames conforming to the general shape of the tunnel interior, a plurality of pistoncylinder units attached between the two frames for effecting relative displacement, and a plurality of elongated plank members arranged side by side around the outer peripheries of the frames to form a lining for the tunnel, the improvement therein comprising locking means for selectively locking and unlocking the elongated plank members to the frames to permit selected plank members to be moved forward lengthwise of the tunnel, said locking means comprising:

a. the second of the two frames having a plurality of second locking pins mounted thereon, said second locking pins being independently movable radially; and

b. the elongated plank members each having a plurality of longitudinally spaced apart second locking pin receiving apertures formed on the interior plank surface, said second locking pins being selectively extended into said second apertures to permit selected plank members to be moved forwardly by said second frame, said second locking pins being retracted out of said second apertures to permit said second frame to be moved rearwardly without moving the plank members.

2. An apparatus according to claim 1, wherein the first of the two frames has a plurality of first locking pins mounted thereon, said first locking pins being movable radially, said first locking pins being dissimilar in form from said second locking pins on said second frame.

3. An apparatus according to claim 2, wherein said movable first locking pins are spring-biased toward said plank member first apertures.

4. An apparatus according to claim 2, wherein the first of the two frames has a plurality of first locking pins being movable radially, and wherein the elongated plank members each has a plurality of longitudinally spaced apart first locking apertures formed on the interior plank surface, said first locking pins being extended into said first apertures to lock the plank members in place.

5. An apparatus according to claim 4, wherein said first apertures have guide surfaces engageable by said first pins, said guide surfaces camming said first pins out of said first apertures as the plank member is moved in either direction lengthwise of the tunnel.

6. An apparatus according to claim 1, wherein said second locking pins are manually settable into three different operating positions, the first position providing that said second locking pin is retracted entirely from said second aperture, the second position providing that said second locking pin is inserted into said second aperture and locks the associated plank member against movement in one direction relative to the second frame, the third position providing that said second locking pin is inserted into said second aperture and locks the associated plank member against movement in the other direction relative to the second frame.

7. An apparatus according to claim 5, wherein said first aperture guide surfaces are inclined with respect to the tunnel axis, and said first locking pin has end surfaces which are inclined for camming engagement with said first aperture guide surfaces.

8. An apparatus according to claim 7, wherein said first aperture guide surfaces include a forward surface portion and a rearward surface portion, said forward portion being inclined less than said rearward portion relative to the tunnel axis, and said rearward portion being inclined at substantially the same angle as that of said first locking pin end surfaces.

9. An apparatus according to claim 8, wherein said forward surface portion is inclined within the range of 15 to 25 relative to the tunnel axis, and said rearward surface is inclined approximately 45 relative to the tunnel axis.

10. An apparatus according to claim 3, wherein said first locking pins are spring-biased toward said first locking apertures by means of a stack of cup springs, and adjustable means are provided for modifying the amount of force exerted by said stack of cup springs on said first locking pins.

11. An apparatus according to claim 1, wherein the first substantially circular frame has an I-shaped crosssection, the axis of said first locking pins being parallel to the central web of said l-shaped cross-section.

12. An apparatus according to claim 1, wherein the second frame is provided with a plurality of guide bushes, said second locking pins being slidably and rotatably guided within said guide bushes, each said second locking pin having a free outer end, said outer end having one face extending parallel to the axis of said second locking pin, said outer end having another adjoining face inclined with relation to said one face, and the plank member second locking pin receiving apertures having guide faces selectively engageable with said locking pin faces.

13. An apparatus according to claim 12, wherein said guide faces of each said second aperture each include two spacedapart faces extending parallel to the axis of said second locking pin, said two parallel aperture guide faces being engageable with said second locking pin parallel faace, said guide faces of each said second aperture each further including two adjoining inclined faces which converge together towards said second locking pin, said two inclined aperture guide faces being engageable with said second locking pin inclined face.

14. An apparatus according to claim 6, wherein the second frame is provided with a plurality of guide bushes, said second locking pins being slidably and rotatably guided within said guide bushes, each said second locking pin having a free outer end, said outer end having one face extending parallel to the axis of said second locking pin, said outer end having another adjoining face inclined with relation to said one face, and the plank member second locking pin receiving apertures having guide faces selectively engageable with said locking pin faces, each of said guide faces of each said second aperture each including two spaced-apart faces extending parallel to the axis of said second locking pin, said two parallel aperture guide faces being engageable with said second locking pin parallel face, said guide faces of each said second aperture each further including two adjoining inclined faces which converge together towards said second locking pin, said two inclined aperture guide faces being engageable with said second locking pin inclined face.

15. An apparatus according to claim 14, wherein each said second locking pin has an inner end, said inner end being provided with a lever for rotating said locking pin into different operating positions, said locking pin being rotated 180 to bring said locking pin parallel face from engagement with one said aperture parallel face into engagement with the other said aperture parallel face, the second frame further having semicircular cams engageable by said levers intermediate the 0 and positions of said levers, said cams causing said locking pins to be retracted from their associated said apertures.

16. An apparatus according to claim 15, wherein the second frame has a plurality of common springs mounted thereon, each said spring engaging the locking pin inner ends of two adjacent locking pins.

17. An apparatus according to claim 12, wherein the second substantially circular frame has a hollow rectangular cross-section, said guide bushes extending between the inner and outer walls of the second frame. 

1. In an apparatus for use in driving tunnels or the like, the apparatus including two parallel, spaced-apart, substantially circular frames conforming to the general shape of the tunnel interior, a pLurality of piston-cylinder units attached between the two frames for effecting relative displacement, and a plurality of elongated plank members arranged side by side around the outer peripheries of the frames to form a lining for the tunnel, the improvement therein comprising locking means for selectively locking and unlocking the elongated plank members to the frames to permit selected plank members to be moved forward lengthwise of the tunnel, said locking means comprising: a. the second of the two frames having a plurality of second locking pins mounted thereon, said second locking pins being independently movable radially; and b. the elongated plank members each having a plurality of longitudinally spaced apart second locking pin receiving apertures formed on the interior plank surface, said second locking pins being selectively extended into said second apertures to permit selected plank members to be moved forwardly by said second frame, said second locking pins being retracted out of said second apertures to permit said second frame to be moved rearwardly without moving the plank members.
 2. An apparatus according to claim 1, wherein the first of the two frames has a plurality of first locking pins mounted thereon, said first locking pins being movable radially, said first locking pins being dissimilar in form from said second locking pins on said second frame.
 3. An apparatus according to claim 2, wherein said movable first locking pins are spring-biased toward said plank member first apertures.
 4. An apparatus according to claim 2, wherein the first of the two frames has a plurality of first locking pins being movable radially, and wherein the elongated plank members each has a plurality of longitudinally spaced apart first locking apertures formed on the interior plank surface, said first locking pins being extended into said first apertures to lock the plank members in place.
 5. An apparatus according to claim 4, wherein said first apertures have guide surfaces engageable by said first pins, said guide surfaces camming said first pins out of said first apertures as the plank member is moved in either direction lengthwise of the tunnel.
 6. An apparatus according to claim 1, wherein said second locking pins are manually settable into three different operating positions, the first position providing that said second locking pin is retracted entirely from said second aperture, the second position providing that said second locking pin is inserted into said second aperture and locks the associated plank member against movement in one direction relative to the second frame, the third position providing that said second locking pin is inserted into said second aperture and locks the associated plank member against movement in the other direction relative to the second frame.
 7. An apparatus according to claim 5, wherein said first aperture guide surfaces are inclined with respect to the tunnel axis, and said first locking pin has end surfaces which are inclined for camming engagement with said first aperture guide surfaces.
 8. An apparatus according to claim 7, wherein said first aperture guide surfaces include a forward surface portion and a rearward surface portion, said forward portion being inclined less than said rearward portion relative to the tunnel axis, and said rearward portion being inclined at substantially the same angle as that of said first locking pin end surfaces.
 9. An apparatus according to claim 8, wherein said forward surface portion is inclined within the range of 15* to 25* relative to the tunnel axis, and said rearward surface is inclined approximately 45* relative to the tunnel axis.
 10. An apparatus according to claim 3, wherein said first locking pins are spring-biased toward said first locking apertures by means of a stack of cup springs, and adjustable means are provided for modifying the amount of force exerted by said stack of cup springs on said first locking pins.
 11. An apparatus according to claim 1, wherein the first substantially circular frame has an I-shaped cross-section, the axis of said first locking pins being parallel to the central web of said I-shaped cross-section.
 12. An apparatus according to claim 1, wherein the second frame is provided with a plurality of guide bushes, said second locking pins being slidably and rotatably guided within said guide bushes, each said second locking pin having a free outer end, said outer end having one face extending parallel to the axis of said second locking pin, said outer end having another adjoining face inclined with relation to said one face, and the plank member second locking pin receiving apertures having guide faces selectively engageable with said locking pin faces.
 13. An apparatus according to claim 12, wherein said guide faces of each said second aperture each include two spacedapart faces extending parallel to the axis of said second locking pin, said two parallel aperture guide faces being engageable with said second locking pin parallel faace, said guide faces of each said second aperture each further including two adjoining inclined faces which converge together towards said second locking pin, said two inclined aperture guide faces being engageable with said second locking pin inclined face.
 14. An apparatus according to claim 6, wherein the second frame is provided with a plurality of guide bushes, said second locking pins being slidably and rotatably guided within said guide bushes, each said second locking pin having a free outer end, said outer end having one face extending parallel to the axis of said second locking pin, said outer end having another adjoining face inclined with relation to said one face, and the plank member second locking pin receiving apertures having guide faces selectively engageable with said locking pin faces, each of said guide faces of each said second aperture each including two spaced-apart faces extending parallel to the axis of said second locking pin, said two parallel aperture guide faces being engageable with said second locking pin parallel face, said guide faces of each said second aperture each further including two adjoining inclined faces which converge together towards said second locking pin, said two inclined aperture guide faces being engageable with said second locking pin inclined face.
 15. An apparatus according to claim 14, wherein each said second locking pin has an inner end, said inner end being provided with a lever for rotating said locking pin into different operating positions, said locking pin being rotated 180* to bring said locking pin parallel face from engagement with one said aperture parallel face into engagement with the other said aperture parallel face, the second frame further having semi-circular cams engageable by said levers intermediate the 0* and 180* positions of said levers, said cams causing said locking pins to be retracted from their associated said apertures.
 16. An apparatus according to claim 15, wherein the second frame has a plurality of common springs mounted thereon, each said spring engaging the locking pin inner ends of two adjacent locking pins.
 17. An apparatus according to claim 12, wherein the second substantially circular frame has a hollow rectangular cross-section, said guide bushes extending between the inner and outer walls of the second frame. 